My new 5D has three hot pixels but only on very long exposures (>30s). Obviously only visible in some circumstances (large prints, even tone where the hot pixels are).
Something I have to live with and clone out? Or straight back to the supplier?
For above 30 seconds? Quite acceptable. There are pixel correction tools in various PP software or you could clone it out. Canon could do a remapping for you, but that might cost money and it doesn't physically "fix" the hot pixel(s), just instructs the sensor to do an interpolation from the surrounding adjacent pixels to substitute for the hot pixel.
I would say enjoy your 5D and don't worry about it.
OutsideShooter wrote:
What exactly does one notice from remapping a sensor? I've not heard of this.
chips have defects
if a chip has enough it ends up in the trash
if not the defects get "mapped" meaning that that space is interpolated rather than actually recorded
basically the bad pixel value is guessed based on the surrounding good pixels
it is my understanding that this happens with all chips and it isnt a big deal
i am not a chipmaker but i play one on the internet
I'm assuming Canon can get your camera re-mapped if this is important to you. In the first year of my G2 Powershot's life, it developed more and more red pixels, so I got it remapped before the warranty expired (can't remember if it was covered by the warranty or not), and the difference was like night and day. They run dark frame test images through a program which does stats (standard deviations, median values and top 'x' hot pixels), before and after, and the numbers matched what I was seeing in my shots. I was very impressed with the service (Canon in Melbourne Australia about 5 years ago)
Another vote for the cap-on sensor clean method. My 2nd 5D is under a month old and had one very bright green pixel visible on every image - a quick try of this method and it was gone. Big thumbs up
Lord Fluff wrote:
Another vote for the cap-on sensor clean method. My 2nd 5D is under a month old and had one very bright green pixel visible on every image - a quick try of this method and it was gone. Big thumbs up
OK, no answer. So I'll try Lord Fluff. What is the actual difference you can see? Is it possible to post any two comparison shots?
Might be off topic, but if you are shooting RAW and using Adobe Camera RAW (ACR) to process your files, ACR automatically removes hot pixels while processing RAW files.
OutsideShooter wrote:
OK, no answer. So I'll try Lord Fluff. What is the actual difference you can see? Is it possible to post any two comparison shots?
I will see what I can do, but in essence I had one vivid green pixel on every picture in the same position - this was visible at about 30% view size and above. Now it has gone. Who knows how this works, but it does. I will see if I can sort out 100% crops, though of course finding the 1 fixed pixel will be tricky and there is no way I can show you a before and after as I could never take the same photos again!
Lord Fluff, no problem with the before/after as I now understand the principle of hot pixels. Had never heard the term or if I had, it just flew by. I was envisioning a better IQ overall somehow. Thanks for the description. These are not the kind of things we notice when printing, but when PP works is being done. I'll keep my eye open but I hope I never see one.
But like photogenix said:
I'm assuming Canon can get your camera re-mapped if this is important to you. In the first year of my G2 Powershot's life, it developed more and more red pixels, so I got it remapped before the warranty expired (can't remember if it was covered by the warranty or not), and the difference was like night and day.
That's worrisome as it sounds like photodiode cells on the sensor temporarily lose their ability to produce more than one color. Remapping resets them. How utilizing "Clean Sensor" Mode does this is a mystery to me, as all it does from what I've read is to lift the mirror & place a small electrical charge to the sensor. But these small electrical charges are done every time the shutter is depressed also, only this is being done without any light introduction.
I am assuming this is done without a lens, with the body cap? And is this unique to a specific series of bodies?
Be sure to turn the long exposure noise reduction feature on for these long exposures. It makes a big difference. You'll see a fair number of hot pixels without it, especially if you photo includes a lot of dark areas. With the feature enabled you will still likely have some noise, but the hot pixel situation will be largely tamed.
The only downside is that the camera takes a second "dark frame" exposure after each shot, and the second one takes just as long as the first.
Last April I was doing night photography on the Racetrack Playa in Death Valley and some exposures were around 10 minutes long... followed by a very relaxing 10 minute wait on the moonlit playa while the dark frame exposure completed itself.
When you do the sensor clean thing with the cap on, can anyone verify that an actual "remap" is being done? It occurs to me that all that is really happening is the static charge on the sensor is being dissipated somehow in preparation for cleaning. I say this because some people (I am one of them) have had great success with this method while others have not. If an actual remap where being done shouldn't it work very consistently?
